Icariin protects against intracerebral hemorrhage in mice by enhancing neuroprotection

Intracerebral hemorrhage (ICH) is a major type of stroke associated with high rates of mortality and long-term disability, often leading to inflammation, brain edema, and neuronal loss. Icariin (ICA) is the primary active compound extracted from Herba epimedii, and it possesses several pharmacological effects including anti-inflammatory, antioxidant and anti-apoptotic properties. However, its neuroprotective capacity and mechanisms in ICH remain unknown. This study investigates the neuroprotective potential of ICA in an ICH mouse model. A total of 108 C57BL/6 mice were randomly assigned to three groups: sham group ( n = 36), ICH + vehicle group ( n = 36), and ICH + ICA group ( n = 36). ICH was induced in the ICH + Vehicle and ICH + ICA groups through injection of collagenase type VII into the basal ganglia. The ICH + ICA group was administered ICA (60 mg/kg/day) intraperitoneally for three consecutive days. Neurological assessment was conducted using the corner test and modified neurological severity scores. TUNEL (terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling) staining was performed to evaluate brain cell death. Brain water content, Western blot, Evans blue (EB) dye extravasation, and immunofluorescence staining were conducted 3 days post-ICH. ICA treatment significantly alleviated brain edema and enhanced neurological function in mice three days post-ICH. Immunofluorescence results revealed that ICA decreased microglia and astrocyte activation and reduced neutrophil infiltration. Western blot results demonstrated that ICA maintained blood-brain barrier (BBB) integrity by decreasing the loss of tight junction proteins, including Occludin and Zonula occludens-1. ICA also lowered matrix metalloproteinase-9 and the proinflammatory cytokines tumor necrosis factor-α and interleukin-1β. TUNEL staining showed a reduction in neuronal cell death with ICA, linked to enhanced level of the anti-apoptotic B-cell lymphoma 2 (Bcl-2) protein and reduced expression of the pro-apoptotic Bcl-2-associated X (Bax) protein. ICA exhibits significant neuroprotective effects in mice following ICH by reducing neuroinflammation, maintaining BBB integrity, and attenuating brain cell death.